The invention relates to a multispeed drive hub with more than three speeds for a bicycle.
A five-speed drive hub for a bicycle, having an integral back pedal brake device, is known from DE-A-34 40 071. The drive hub comprises a hub sleeve mounted for rotation on a hub axle and adapted to be driven, via a multistage planetary gear unit, by a drive member rotatable on the hub axle relative to the hub axle and the hub sleeve. The entire planetary gear unit is accommodated in the hub sleeve and has planet wheels in the form of step wheels whose steps are adapted to be alternately coupled, with the aid of a manually operated control device, to two sun wheels, which in turn can be alternately fastened for rotation with the hub axle. In the known drive hub the cost of manufacture, assembly and adjustment of the two-stage planetary gear unit is comparatively high. Moreover, in its overdrive positions the planetary gear unit reduces the achievable braking moment of the back-pedal brake device.
The problem underlying the invention is that of providing a multispeed hub which has more than three speeds and an integral back-pedal device and which entails the least possible expense for constructional parts while achieving an improved braking action. In particular, with low costs for constructional parts, it should be ensured that the brake can be applied with an increased back-pedal braking moment irrespective of the instantaneous control position of the drive hub. The invention also seeks to reduce the cost of assembling the drive hub.